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- Samson Abramsky, Simon J. Gay, Rajagopal Nagarajan
- NATO ASI DPD
- 1996

We propose Interaction Categories as a new paradigm for the semantics of functional and concurrent computation. Interaction categories have speciications as objects , processes as morphisms, and interaction as composition. We introduce two key examples of interaction categories for concurrent computation and indicate how a general axiomatisation can be… (More)

- Simon J. Gay, Rajagopal Nagarajan, Nikolaos Papanikolaou
- ArXiv
- 2005

We establish fundamental and general techniques for formal verification of quantum protocols. Quantum protocols are novel communication schemes involving the use of quantum-mechanical phenomena for representation, storage and transmission of data. As opposed to quantum computers, quantum communication systems can and have been implemented using present-day… (More)

- Garry Bowen, Rajagopal Nagarajan
- IEEE Transactions on Information Theory
- 2005

In Shannon information theory, the capacity of a memoryless communication channel cannot be increased by the use of feedback from receiver to sender. In this correspondence, the use of classical feedback is shown to provide no increase in the unassisted classical capacity of a memoryless quantum channel when feedback is used across nonentangled input… (More)

- Simon J. Gay, Rajagopal Nagarajan
- POPL
- 2005

We define a language CQP (Communicating Quantum Processes) for modelling systems which combine quantum and classical communication and computation. CQP combines the communication primitives of the pi-calculus with primitives for measurement and transformation of quantum state; in particular, quantum bits (qubits) can be transmitted from process to process… (More)

We introduce a model-checking tool intended specially for the analysis of quantum information protocols. The tool incorporates an efficient representation of a certain class of quantum circuits, namely those expressible in the so-called stabiliser formalism. Models of protocols are described using a simple, imperative style simulation language which… (More)

- Samson Abramsky, Simon J. Gay, Rajagopal Nagarajan
- Banff Higher Order Workshop
- 1995

Many diierent notions of \property of interest" and methods of verifying such properties arise naturally in programming. A general framework of \Speciication Structures" is presented for combining diierent notions and methods in a coherent fashion. This is then applied to concurrency in the setting of Interaction Categories. As an example, we present a type… (More)

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- Simon J. Gay, Rajagopal Nagarajan
- Mathematical Structures in Computer Science
- 2006

1 and R a j a g o p a l N a g a r a j a n 2 † We define a language CQP (Communicating Quantum Processes) for modelling systems which combine quantum and classical communication and computation. CQP combines the communication primitives of the pi-calculus with primitives for measurement and transformation of quantum state; in particular, quantum bits… (More)

— This paper discusses the use of computer–aided verification as a practical means for analysing quantum information systems; specifically, the BB84 protocol for quantum key distribution is examined using this method. This protocol has been shown to be unconditionally secure against all attacks in an information–theoretic setting, but the relevant security… (More)

- Simon J. Gay, Rajagopal Nagarajan
- LICS
- 1995

We propose a typed calculus of synchronous processes based on the structure of interaction categories. Our aim has been to develop a calculus for concurrency that is canonical in the sense that the typed-calculus is canonical for functional computation. We show strong connections between syntax, logic and semantics, analogous to the familiar correspondence… (More)